This function works fine at the top of the page. However, the one at the bottom of the page always closes after the first digit is entered. When tapping the drop down a second time, the first digit is there and we can enter a second and third digit without problems. This is accessing from an iPad, if that is relevant for coding.
I can't reproduce that on my iPad. It's working the same at the top and the bottom. My iPad is an older model though so maybe that's got something to do with it.